Photographic developer and method of developing



Patented Aug. 7, 1934 PATE roFFicE,

IPHOTOGR APH IC DEVELOPER AND METHOD Y, 0F DEVELOPING Harlan L. Trumbull, Hudson, Ohio, assignor to Q y I The B. F. Goodrich Company, NewYork, N. -Y.,

' a corporation tr New York No Drawing. Application January 23, 1932, I

Serial No. 588,491

8 Claims.

This invention relates to the art of photography, and particularly to the development of latent images in silver halide photographic emulsions.

It has been the general practice to develop silver halide photographic emulsions such as those on the familiar dry plates, photographic films, bromide and gas-light papers, etc., by'immersing them in a mildly alkaline solution of a reducing agent such as hydroquinone, pyrogallol, monomethyl p-aminophenol, glycine, etc. The chief object of this invention then is to provide a new class of developing agents which exhibit certain distinct advantages over the previously known Idevelopers. Another object is to provide a class of developers which are far less expensive than the ones which are now in common use. Other objects will be evident from the following description of the invention.

The new developers which are employed in accordance with this invention are members of a class of substances which may be designated generally as hydroxy substituted diarylamines. The preferred members of the class are diarylamines which contain no substituents other than hydrocarbon groups and a single hydroxyl group, that is, N aryl substituted aminophenols.

The following substances, for example, are typical members of the class described above: p- .hydroxy diphenylamine, m-hydroxy diphenylamine, ohydroxy diphenylamine, p-hydroxy phenyl p-toluidine, p-hydroXy phenyl o-toluidine, the hydroxy phenyl Xylidines,'the hydroxy phenyl napthtylamines, the hydroxy phenyl bip-henylamines (Xenylamines), the N phenyl amino cresols, the N phenyl amino naphthols, the N tolyl amino cresols, the hydroxy phenyl anisidines and phenetidines, the dihydroxy diarylamines such as p,p'-dihydroxy diphenylamine, and even compounds containing more than one amino group, such as p-hydroxy p'-amino diphenylamine, p-hydroxy p-dimethylamino diphenylamine, or p-hydroxy P'-phenylamino diphenylamine. These developers may obviously be addied to the developing solution as the free base or as the hydrochloride or other convenient salt. The acid of such salts will generally be neutralized by the alkaline salts ordinarily used in developing solutions.

Thenew developers of the class described above may be used for the development of photographic images in the ordinary manner, preferably in a weakly alkaline solution. They possess a higher molecular weight than most of the previously known developers, hence somewhat greater proportions may be required, but this necessity is offset by the lower cost of many of these'new developers and the superior resultsattained by their use. 7

As a specific example of one embodiment of this invention, a developing solution is prepared containing as developer p-hydroxy diphenylamine, according to the following formula:

Plates 0r films which have been given a normal exposure to light are developed by immersion in the solution for from 5 to 25 minutes at a temperature of about 18 to 25 C. to F.). They are then washed, fixed in a solution of sodium hyposulphite, and washed thoroughly, in the usual manner. The photographic reproductions obtained in this manner are soft and pleasing, the details being well brought out by the action of the developer, while at the same time the contrast is good and the whites are clear. The new developer allows an unusual latitude in the degree of exposure, good results being obtained even with emulsions which are considerably under or over-exposed. I Thev new developers of this invention are admirably adapted for tank development, because of their tendency to correct the efifects of improper exposure. They are particularly desirable for landscape or portrait work where the ability to reproduce detail is of greater importance than the production of the utmost degree of contrast. They may be kept in stock almost indefinitely, either dry or in the form of a solution, for they are far more stablethan the ma-. jority of the developers now incommon use, and do not deteriorate on standing, even in moderately strong sunlight.

Although a specific embodiment of the inven-v tion has been described with considerable particularity, it is to be understood that this invention isno t limited thereby but that it is susceptible of numerous variations within the scope of the appended claims, as will be obvious to those skilled in the art. In particular, the new. developers of this invention may be used in conjunc-' tion with other known developers, or with other salts, acids, or alkalies than those hereinabove mentioned, to modify the properties of the developing solution or of the photographic images 6. The method of developing photographic images which comprises treating a silver halide photographic emulsion which has been exposed to the light with a solution comprising a monohydroxy substituted diphenylamine.

"I. The method of developing photographic images which comprises treating a silver halide photographic emulsion which has been exposed to the light with a solution comprising p-hydroxy diphenylamine.

8. The method of developing photographic images which comprises immersing a silver halide photographic emulsion which has been exposed to the light in an aqueous alkaline solution comprising p-hydroxy diphenylamine.

HARLAN L. 'IRUMBULL. 

